This is NASA's audacious plan to land humans on Mars within your lifetime

NASAWASHINGTON, D.C. — In sharp contrast to the cynical outlook that politicians, lobbyists, and reporters generally have about space travel in this city, the tone inside the Smithsonian's Future Is Here Festival on April 24 was unabashedly optimistic.

There, NASA officials shared their detailed plans to land humans on Mars as soon as 15 years from now.

But the space agency seems serious this time. President Obama challenged NASA to get astronauts to Mars in the 2030s. And while other presidents have done the same since the Apollo missions returned from the moon, NASA says that it's finally ready for its Mars shot.

"We're closer than we've ever been to humans stepping on Mars," NASA's deputy administrator, Dava Newman, said at the conference.

"This sounds good, but it is actually a journey to nowhere until we have that budget and we have the schedule and we have the deadlines," Rep. Lamar Smith (R-TX) said during a congressional hearing after the report was released.

Newman and other NASA administrators shared new details at the Smithsonian conference, though, filling in some of the blanks to respond to Smith's and others' criticisms.

Here's how the agency plans to get humans on Mars within our lifetimes.

The plan

NASA and Lockheed Martin have already built the spacecraft that will take humans to Mars, called Orion. But it has to go through a few more tests before that happens.

All of the missions in the next two decades are building up to be able to land humans on Mars in the 2030s.

Newman said the journey is divided into three phases: Earth-dependent, proving ground, and Earth-independent.

Earth-dependent (today)

NASA will continue to test the effects of space on the human body and conduct experiments aboard the International Space Station (ISS).

Astronaut Scott Kelly's year in space was a big part of this phase, since they'll compare what he went through with his twin brother who stayed on the ground.

The Orion spacecraft awaits liftoff during its 2014 flight test aboard a Delta IV rocket.NASAIn 2018, NASA plans to launch Orion into orbit atop a new Statue of Liberty-size rocket, called the Space Launch System (SLS). The goal is to see if SLS works and how well Orion holds up to radiation in space. The spacecraft will be uncrewed and the mission will last about three weeks.

Proving ground (2020s)

The first crewed Orion mission is scheduled for 2023, when four astronauts will get test the spacecraft themselves.

To give them something important to do, NASA is launching an uncrewed mission called the Asteroid Redirect Mission. The spacecraft should arrive at a nearby asteroid and grab a sample by 2018, then bring it into the moon's orbit by 2023 so the astronauts can go study the rock. This mission will help NASA figure out how humans and robots can work together on deep space missions like they'll have to on Mars, Newman said.

During the 2020s, NASA also plans to test deep space habitats, possibly on the moon, to experiment with how they'll have to design habitats for the surface of Mars.

It's around this time — the mid-2020s — when NASA's plans start to get a little fuzzier and less concrete.

Earth-independent (2030s)

To the critics' lament, plans get even more speculative in the 2030s.

NASA wants to launch a crewed, round-trip mission to Mars aboard Orion — but that's about all the details the agency has confirmed so far.

Newman emphasized the importance of "round-trip:" They're going to bring the astronauts back to Earth. This mission will take three years to complete, and will hopefully be the first of many before we set up a permanent colony on Mars.

But NASA has a lot to figure out before we get to that point.

The challenges

Skye Gould/Tech Insider

Keeping astronauts safe

When humans leave the protective shielding that Earth provides, we are highly susceptible to the dangers of space. We evolved on Earth, after all — we're not built for interplanetary travel.

One of the biggest concerns NASA has with sending astronauts on deep space mission is the dose of radiation they'll receive out there.

High energy particles from the sun, called coronal mass ejections, and those from outside the solar system, called cosmic rays, can bombard spacecraft with powerful radiation. In turn, this can increase the risk of cancer for the astronauts inside.

NASA currently sets a limit for the increase in risk that astronauts would develop and die from cancer, and our current technology wouldn't be able to keep astronauts below that dose on a round-trip to Mars. Our spacecraft will need better shielding, or we'll have to develop drugs to keep this risk at bay, or both.

But an increased cancer risk is just one of the many health problems that can happen in space. Prolonged space travel can also make humans lose bone density and muscle mass, and it may affect their eyesight. Mental health could also be an issue in a confined spacecraft.

The technical challenges of launching and landing rockets on Mars are one thing — making sure the astronauts stay healthy enough to complete their mission and come home is a whole other.

Dava Newman models the spacesuit she designed for astronauts to use on the surface of Mars.NASA

Securing money

Convincing Congress to fund far-off missions that lack concrete deadlines is always a struggle, but it's especially tough when that money is for space travel.

NASA has experienced its share of budget cuts in recent years, and the future of funding — particularly with the 2016 election looming — is unclear.

NASA could also partner with ambitious companies planning their own Mars landings, like SpaceX. The agency is increasingly working with industry in a way that is hugely beneficial to both parties, so this could be an economical option.

Like many basic science endeavors, we don't yet know what knowledge we can gain by going to Mars. Did we foresee all the developments in flight systems, communications, and computers that the moon landings, or the shuttle missions, were going to yield? Of course not.

Giving NASA money always takes a bit of faith. We don't know what exploring the universe can teach us.

"We're following our curiosity. ... We don't know where it will take us, but it will bring change, and that itself keeps us alive," NASA engineer Adam Steltzner said at the conference, who led the team that developed the landing system for the Mars Curiosity rover. "The curiosity is in our genes."

The inspiration

First rovers, then humans.NASAFormer NASA astronaut Tony Antonelli has asked schoolchildren if they think we're going to land humans on Mars soon. To them, it's not a question — it's a given.

Kids may be the only ones who are as optimistic about these missions as NASA administrators are. They know we'll get "boots on the ground" on Mars within their lifetimes. Some of them might even be the astronauts who make it there.

The rest of the general public is another story. Importantly for NASA, they're the ones who need convincing to drive that final push to get us there, said Antonelli, who's now the chief technologist of exploration systems for Lockheed Martin's civil line of space systems.

"We will not go until the American people and the international community are ready and decide that it is a priority," he told Tech Insider. "I really think what we're missing is a sense of urgency, a sense of purpose, and just pushing out and doing it."

Little kids know it will happen. NASA and its partners are ready to go. Now the public has to get on board to convince their representatives in Washington, too.

"We have nearly enough information to be able to support humans going to Mars," NASA's Planetary Science Director Jim Green said at the festival. "It's not a matter of if. It's a matter of when."